Method and device for demounting a turbine blade

ABSTRACT

The invention relates to a method and a device for demounting a turbine blade ( 1 ) out of an axial groove ( 3 ) of a rotor ( 8 ) or stator. The turbine blade ( 1 ) is demounted with a hydraulic device ( 9, 10 ) by means of a hooked slide ( 4 ) which is located in a gap ( 7 ) between the blade base of the blade root ( 2 ) and the groove bottom of the axial groove ( 3 ). At the same time, the hooks ( 5 ) of the hooked slide ( 4 ) engage into clearances which are located at the blade root ( 2 ).

[0001] The invention relates to a method for demounting a turbine bladeaccording to the preamble of claim 1. The invention also relates to adevice for applying the method.

[0002] In the demounting of turbine blades which are arranged in agroove on the rotor or on the stator of the thermal turbomachine, it isknown from the prior art to demount these by means of a so-calledexpeller. This expeller, which is usually operated pneumatically and isalso designated as a pneumatic hammer, engages on the root plate in theregion of the profiled issue of the rear side of the turbine blade, inorder to expel the latter out of the axial groove.

[0003] However, this type of demounting has various disadvantages. Sincethere is only a very small amount of space between two rows of movingblades, for example of a gas turbine, the expulsion tool can be appliedto the root plate only at an unfavorable angle to the expulsiondirection. The result of this is that demounting becomes correspondinglytime-consuming and difficult, since the force component expelling theblade root out of the groove is very low. Due to deposits between theaxial groove and the blade root, a high coefficient of friction prevailsbetween the two parts, and this makes it even more difficult to removethe turbine blade. As a result of the unfavorable point of engagementfor the introduction of force, a tilting moment is generated at theblade root and makes it very difficult or even possible to remove theturbine blade. The expulsion tool may also damage a protective layerwhich is present, if appropriate, and which is applied to the surface ofthe turbine blade, even though the tool is equipped at the blade contactpoint with a nylon covering with which an attempt is made to avoiddamage of this kind.

[0004] The object of the invention is to avoid the disadvantagesmentioned. The invention achieves the object of providing a device and amethod which makes it possible to remove a turbine blade in a simplifiedway. Moments on the turbine blade are to be avoided or reduced to aminimum during demounting. A protective layer which is present, ifappropriate, is not to be damaged during demounting.

[0005] According to the invention, in a method according to the preambleof claim 1, this is achieved in that the turbine blade is drawn out ofthe circumferential groove in the axial direction by means of a devicewhich engages on the blade root of the turbine blade.

[0006] Advantageously, the force is generated entirely in the axialdirection, thus virtually eliminating a moment leading to tilting.Moreover, the time for demounting the turbine blades is markedly reducedin this way.

[0007] In a particular embodiment, the turbine blade is demounted bymeans of a hooked slide. The hooked slide is introduced into a gaplocated between the blade base and the groove bottom and is removedthere by means of at least one hook which is anchored in at least oneclearance at the blade root. If present, an existing cooling-air bore ofthe turbine blade may advantageously be used as a clearance.

[0008] A supporting slide advantageously serves additionally to securethe position of the hooked slide during demounting. The turbine bladecan be drawn out by means of the hooked slide by a device which isoperated hydraulically and which is supported on the rotor or stator onsupports next to the hooked slide and the axial groove.

[0009] The method according to the invention is suitable, in particular,for the demounting of guide vanes or moving blades in gas turbines,steam turbines or compressors.

[0010] The invention also relates to a device for applying thedemounting method according to the preamble of claim 8. The device ischaracterized in that the demounting device consists of a hydraulicallyoperated piston generating a tensile force which acts in the axialdirection and which can be transmitted to the blade root of the turbineblade in such a way that it is possible to demount the turbine blade,and, in addition, next to the blade root, on the rotor or stator, meansare present which are connected to the hydraulically driven piston insuch a way that, during the demounting of the turbine blade, they allowsupport with respect to the tensile force generated by the piston. Inaddition, a hooked or supporting slide may be present, which makesdemounting possible.

[0011] In the drawing:

[0012]FIG. 1 shows a section through the blade root of a turbine bladewith a demounting device according to the invention,

[0013]FIG. 2 shows a section through a turbine blade along the lineII-II in FIG. 1,

[0014]FIG. 3 shows a view of a demounting device according to theinvention from above, and

[0015]FIG. 4 shows a section along the line IV-IV in FIG. 3.

[0016] Only the elements essential to the invention are illustrated.Identical elements are given the same reference symbols in differentdrawings.

[0017] The invention relates to a method and a device for demounting aturbine blade 1 out of an axially arranged groove 3 of a rotor 8 or of astator of a thermal turbomachine. The turbine blade 1 may be, forexample, a guide vane or a moving blade of a gas turbine, steam turbineor compressor.

[0018]FIG. 1 shows a section through the blade root 2 of such a turbineblade 1. The turbine blade 1 is equipped, inside, with a cooling system13 which receives cooling air while the thermal turbo machine is inoperation. The cooling air passes through cooling ventilation holes 12,which are located at the blade base, into the cooling system 13.However, this is generally known from the prior art and is notillustrated in any more detail in the figures.

[0019] The demounting of the turbine blade 1 out of the axial groove, asillustrated in FIG. 1, is carried out by means of two slides, a hookedslide 4 and a supporting slide 6. The hooked slide 4 is introduced intoa gap 7 which is located between the blade base and the groove bottom.Hooks 5, which are located on the hooked slide 4, then engage into thecooling-air holes 12 or into other clearances located at the blade base.In a further method step, the supporting slide 6 is introduced under thehooked slide 4. This supporting slide 6 positively adjoins the hookedslide 4 and ensures that the hooked slide 4 is secured in positionduring the demounting of the turbine blade 1.

[0020]FIG. 2 shows a corresponding section through the blade root 2 of aturbine blade 1 along the line II-II in FIG. 1. Both the two slides, thehooked slide 4 and the supporting slide 6 positively adjoining thelatter below it, and the hooks 5 can be seen there. Both are located inthe gap 7 below the blade root 2 between the blade base of the turbineblade 1 and the groove bottom of the axial groove 3.

[0021] As can be seen in FIGS. 3 and 4, in order to demount the turbineblade 1, the hooked slide 4 is connected to a piston 15. Shouldpossibilities be present, this piston 15 could also engage directly onthe turbine blade 1. The turbine blade is drawn out of the axial groove3 via a hydraulic cylinder 9 which is driven by means of a hydraulicpump 10. At the same time, a tensile force applied in the axialdirection acts on the turbine blade 1. So that this tensile force canact on the blade root 2 of the turbine blade 1, the hydraulic cylinder 9is supported on two supports 11 which engage on the rotor 8 next to thehooked slide 4. FIG. 4, which shows a section through the demountingdevice along the line IV-IV in FIG. 3, discloses the arrangement of thetwo supports 11 on the rotor 8 next to the axial groove 3. By thehydraulic cylinder 9 being used, very high forces can be generated andtransmitted to the turbine blade 1.

[0022] The demounting according to the invention of the turbine blade 1,as disclosed in the present description, has various advantages, ascompared with the prior art. Since an axial tensile force acts on theblade root 2, disturbing moments causing tilting of the blade root arevirtually prevented. The reason for this, in particular, is that theline of action of the applied tensile force during the demountingaccording to the invention is appreciably nearer to a desired line ofaction than in the methods known hitherto from the prior art. Thedemounting time is reduced considerably by means of the proposed methodas a result of these facts.

[0023] List of Reference Symbols

[0024]1 Turbine blade

[0025]2 Blade root

[0026]3 Groove

[0027]4 Hooked slide

[0028]5 Hook

[0029]6 Supporting slide

[0030]7 Gap

[0031]8 Rotor

[0032]9 Hydraulic cylinder

[0033]10 Hydraulic pump

[0034]11 Support

[0035]12 Cooling ventilation hole

[0036]13 Cooling system

[0037]14 Blade leaf

[0038]15 Piston

1. A method for demounting a turbine blade (1) which is fastened in anaxially oriented groove (3) of a rotor (8) or stator of a turbomachineby means of a blade root (2), characterized in that the turbine blade(1) is drawn out of the circumferential groove (3) in the axialdirection by means of a device (4, 10, 11, 15) which engages on theblade root (2) of the turbine blade (1).
 2. The demounting method asclaimed in claim 1 , characterized in that the turbine blade (1) isdrawn out, as a result of the tensile force acting in the axialdirection, by means of a piston (15) which is driven by a hydrauliccylinder (9) and which engages directly or indirectly on the blade root(2) of the turbine blade (1), and next to the blade root (2) of theturbine blade (1), on the rotor (8) or stator, supports (11) arepresent, on which the hydraulic cylinder (9) is supported, so that thehydraulic cylinder (9) transmits to the piston (15) the tensile forceacting in the axial direction.
 3. The demounting method as claimed inclaim 2 , characterized in that a hooked slide (4) is introduced into agap (7) located between the blade base and the groove bottom and isanchored to the blade root (2) there by means of at least one hook (5)which is located in at least one clearance (12) located at the bladebase, and the turbine blade (1) is drawn out by means of the hookedslide (4) and the piston (15) fastened to the latter.
 4. The demountingmethod as claimed in claim 3 , characterized in that a supporting slide(6) is introduced under the hooked slide (4) before the turbine blade(1) is demounted by means of the hooked slide (4).
 5. The demountingmethod as claimed in claim 3 , characterized in that the at least onehook (5) of the hooked slide (4) is anchored in at least one coolingventilation hole (12) which is located in the form of a clearance (12)at the blade base.
 6. The demounting method as claimed in one of thepreceding claims, characterized in that the turbine blade (1) is a guidevane or moving blade of a gas turbine, steam turbine or compressor.
 7. Ademounting device for carrying out the demounting method as claimed inone of claims 1 to 6 , characterized in that the demounting deviceconsists of a hydraulically operated piston (15), by means of which atensile force acting in the axial direction can be generated, which canbe transmitted to the blade root (2) of the turbine blade (1) in such away that it is possible to demount the turbine blade (1), and, inaddition, supports (11) are present, which are connected to thehydraulically operated piston (15) in such a way that, during thedemounting of the turbine blade (1), they allow support with respect tothe tensile force acting on the piston (15).
 8. The demounting device asclaimed in claim 7 , characterized in that, during the demounting of theturbine blade (1), the hydraulically operated piston (15) is connectedto a hooked slide (4) which is detained at the blade base of the bladeroot (2) by means of at least one hook (5) at a clearance (12), thehooked slide (4) being located in a gap (7) between the blade base andthe groove bottom.
 9. The demounting device as claimed in claim 8 ,characterized in that, during the demounting of the turbine blade (1), asupporting slide (6) is arranged below the hooked slide (4).